Various apparatus which support human forearms and wrists have heretofore been devised.
For example U.S. Pat. No. 5,072,905 (Hyatt) discloses an apparatus for clamping to a table or desk to support the wrist and forearm of a person. The wrist and forearm support apparatus comprises a cushioned wrist support member having a pair of cushioned armrest members, pivotally connected thereto for adjustment to angular positions providing optimal support for an individual user, and a clamping mechanism disposed at forward ends of the armrests support members for attaching the wrist support member and the armrest as a unitary structure to the edge of a table or desk.
Furthermore, U.S. Pat. No. 4,576,351 (Brink) discloses a portable stroke victim's armrest which provides a multi-positional means of comfort for the victim's arm and in particular to prop the victim's arm at an incline to prevent accumulation of fluids in the hand and wrist area. The portable stroke victim's armrest comprises a support member having a generally horizontal shelf member and a generally vertical brace member emanating downwardly therefrom at substantially right angles from one side of the shelf member, a "U"-shaped height adjusting member operatively mounted with said support member being adapted to securely position the portable stroke victim's armrest on the arm of a chair, sofa, or the like and further adapted to raise and lower the ends of the support member to achieve various heights and angles, a stub-shaft located medially between the ends of the leg members, connected therebetween and forming with leg members a guide for stably receiving an arm of a chair, a contoured cushion arm support movably coupled to the support member including a cushioned substantially horizontal support and a cushioned upwardly extending wall along the horizontal support outer edge and being substantially at right angles therewith, a substantially horizontal support evolving into an elevated arcuate end portion which is contoured for and accommodates the hand and wrist area in an elevated position with respect to horizontal to thereby enhance the natural gravity encouraged flow of fluids necessary to the physical well-being of stroke victims.
Furthermore, U.S. Pat. No. 4,575,152 (McLaughin) discloses a padded member and method of making same. This patent relates to a padded member including a beam support enclosed in a cushion and a method of making the padded member. The method includes providing a core having a projecting portion and partially encircled by a sleeve to assume the shape of a beam support and molding a cushion about the core and sleeve to form an opening in the cushion spaced from the sleeve and a flexible cushion portion adjacent the opening accompanying flexing of the cushion for removal from the core and application to a beam support.
Furthermore, U.S. Pat. No. 3,950,027 (Wilson) an armrest for a dental chair. This patent discloses an adjustable armrest which can be rotated ninety degrees in a horizontal plane about a vertical axis to permit easier entry and exit of a patient to and from the dental chair. The armrest is automatically locked at either the forward position or the ninety degree position and is unlocked by lifting vertically on the armrest. A single set screw connects the armrest to the dental chair.
Furthermore, U.S. Pat. No. 4,025,112 (Hale) discloses a medical stool. This patent comprises a seat, framework means connected to and supporting the seat, and an armrest or equipment support being connected by an intermediate generally horizontally disposed member which is joined to the support frame and the underside of the armrest or equipment support by connectors. When the interrelationship of the connectors is compressed, rotation at the connector is obviated, whereas the opposite is true when the connectors are relatively loose, the connectors accommodating ready separation of the armrest from the intermediate member and the intermediate member from the support frame.
Furthermore, U.S. Pat. No. 4,277,102 (Aaras et al) discloses a chair having a seat portion, a back rest and armrest. The armrests are individually supported on arms mounted on the seat support member. The connection of the armrest to the support arms and the support arms to the seat body is through the use of universal joints allowing movement in all directions.
Moreover, U.S. Pat. No. 4,822,103 (Stenvall) discloses an armrest device for relieving loads when performing work by hand and wrist movement. This patent comprises an attachment member for mounting the armrest on a chair, an upper support for supporting the forearm and arranging to be self-positioned while supporting the forearm and work being performed by hand and wrist movements, the support accompanying the hand and wrist movements, an adjustable horizontal guide rail attached to said upper support and movably disposed in longitudinal direction to provide a corresponding adjustment of said support due to the influence of a force generated when the hand is moved forwards or backwards. An adjustable vertical guide rail which is moveable in its longitudinal direction to provide a corresponding adjustment of said support due to the influence of the force generated by the weight of the forearm and by external forces exerted on the forearm.
Finally, U.S. Pat. Nos. 2,950,890 (Hough), 4,688,862 (Fowler et al), 4,482,064 (Berke et al), 4,482,063 (Berke et al) and 4,621,781 (Springer) are all patents which relate to armrests for attachment to office equipment.
Each of the prior devices referred to above present relatively complicated structures having relatively limited use.
It is an object of this invention to produce an improved armrest structure which substantially alleviates repetitive stress injury such as carpal tunnel syndrome.
Repetitive stress injury such as carpal tunnel syndrome is most likely to emerge in individuals engaged in prolonged keyboarding, or other keying-type activities having similar repetitive motion functions. Repetitive stress injuries have large costs associated with them both to the individual having the disorder and to their employer. Recent studies have also disclosed that repetitive stress injuries such as carpal tunnel syndrome are on the increase in North America and that in most cases the disorder is irreversible.
Other objects of the invention will appear hereinafter.
The broadest aspect of this invention relates to an armrest assembly for a chair comprising; a lower arm; an upper arm overlying said lower arm; support shaft means depending from said upper arm, said support shaft means presenting an axis of rotation, for rotational movement of said upper arm about said axis; a support shaft housing associated with said lower arm for receiving said support shaft means for combined rotational and axial movement of said upper arm relative said lower arm about said axis.
It is another aspect of this invention to provide an armrest assembly for a chair comprising; an upper arm having a from end and a back end; support shaft means associated with said upper arm adjacent said front end of said arm, said support shaft means presenting an axis of rotation, for rotational movement of said upper arm about said axis, said support shaft means having: series of multiple depressions at one end of said support shaft means, aligned such that there are four aligned rows having three radially spaced depressions about said axis of rotation, said multiple depressions having a generally circular cross-section; and multiple recesses at another end of said support shaft means; a lower arm joined to said chair, said lower arm having a front end and back end; support shaft housing carried by said lower arm for receiving said support shaft means for relative rotational movement of said upper arm relative said support shaft means about said axis; said upper arm overlying said lower arm in a storage position; said upper arm being generally horizontally disposed relative said generally vertical support shaft means; said support shaft housing having one end closed by a cap, a spring located within said support shaft housing and an opening within said support shaft housing to receive a lever to interact with said recesses in said support shaft means; at another end one or more apertures in the portion of the support shaft housing which extends above the said lower arm, a locator ball received in each aperture, and a securing means encircling the outer radius of the shaft urging the said locator ball against the support shaft, and securing said locator ball in the said depressions on the said support shaft means when engaged, securing certain fixed positions of the said armrest and allowing the said upper arm to be locked and unlocked rotatably by force exerted rotatably on the said upper arm by said user; said lever located within a lever housing, said lever housing abutting said support shaft housing, said lever urging into said opening within said support shaft housing by a lever spring means located between said lever and said lever housing wall.
It is yet another aspect of this invention to provide an armrest assembly for a chair comprising; an upper arm presenting a front end and a back end, having a ridged support means disposed therein and wherein said armrest is cushioned; a lower arm presenting a front end and a back end having a support shaft housing and lever housing disposed therein; a support shaft means generally circular in cross section having at one end thereof, multiple recesses and at the other end thereof, multiple depressions having a generally circular cross section, the end having multiple depressions being affixed to the said rigid support disposed within the said upper arm and the other end placed into the said support shaft housing at said front end of said lower arm, said support shaft means presenting an axis of rotation; means for adjusting the distance of said upper arm relative said lower arm along said axis of rotation and having a support shaft housing disposed in said lower arm, said support shaft housing having one end closed by a cap means, a spring means located within said support shaft housing, and an opening within the wall of the support shaft housing to receive a lever which will interact with the said recesses in said support shaft means and having a lever housing, in said lower arm, said lever located within said lever housing, said lever urging into said opening within the wall of the support shaft housing by a spring means located between said lever and said lever housing wall; means for radially rotating the position of the said upper arm about said axis of rotation to multiple positions, the said support shaft housing having at one end thereof one or more apertures in the portion of the support shaft housing which extends above the said lower arm, a locator ball received in each aperture and a securing means encircling the outer radius of the support shaft housing urging the said locator ball against the support shaft, and securing said locator ball in the said depressions on the said support shaft means when engaged, securing certain fixed positions of the said armrest and allowing said upper arm to be locked and unlocked rotatably by force exerted rotatably on the said upper chair arm.